pinctrl: qcom: sc8180x: gracefully handle missing IO memory resource

pinctrl: qcom: sc8180x: gracefully handle missing IO memory resource

If device was probed with incorrect DT or ACPI tables, the IO memory
resource would be missing and driver would derefernce NULL pointer in
sc8180x_pinctrl_add_tile_resources().  Add simplep check if IO memory
resource was provided to silence Smatch warning:

  drivers/pinctrl/qcom/pinctrl-sc8180x.c:1664 sc8180x_pinctrl_add_tile_resources() error: potentially dereferencing uninitialized 'mres'.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230513113510.177666-1-krzysztof.kozlowski@linaro.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>